A circuit arrangement of this kind is known from German Patent 29 11 998 and corresponding WESEMEYER et al. U.S. Pat. No. 4,455,623.
Booting circuits of this kind are necessary, particularly in motor vehicles, so that the microprocessor and its peripherals are not continuously connected to the vehicle battery in the operating mode, thus discharging the battery if the vehicle is stopped for a relatively long period. On the other hand, even when the vehicle is shut off for such long times, the microprocessor must not be switched off completely, since various functions, such as tripping of the vehicle alarm system, or electric door locking can be kept operative only if they are generally controlled via the microprocessor. Similar problems generally arise in all battery-operated microprocessor systems that must trigger function processes from the state of repose.